Preliminary Study
on Facial Soft Tissue Thickness by Magnetic Resonance Imaging
in Northwest Indians
Daisy
Sahni
Associate Professor of Anatomy
Indar Jit
Emeritus Professor of Anatomy and Forensic Medicine
Madhur Gupta
Professor and Department Head of Anatomy
Paramjeet Singh
Assistant Professor of Radiodiagnosis and Imaging
Sudha Suri
Professor and Department Head of Radiodiagnosis and Imaging
Postgraduate Institute of Medical Education and Research
Chandigarh, India
Sanjeev
Department Head of Biology
Central Forensic Science Laboratory
Chandigarh, India
Harjinder
Kaur
Ph.D Student
Department of Anthropology
Panjab University
Chandigarh, India
Paper
presented at the 9th Biennial Meeting of the International Association
for Craniofacial Identification, FBI, Washington, DC, July 2000.
Abstract.......Introduction.......Materials
and Methods.......Observations
Discussion.......References
Abstract
Facial
soft tissue thickness was measured in 60 northwest Indian adults
(30 women and 30 men) between the ages of 18 and 40 years by
magnetic resonance imaging (MRI). Seven MRI sections were taken
to measure thickness at standard anatomical landmarks--one sagittal
section, one parasagittal section at the level of midorbit, two
coronal sections, and three transverse (axial) sections. Measurements
of facial soft tissues of northwest Indian men were higher than
northwest Indian women except beneath the chin, infraorbital
margin, and lower lip margin. Statistically, sexual differences
in most of the measurements were highly significant. The end
of the nasal opisthocranion and supra M2, however, were insignificant.
Slight asymmetry in two sides was present at the frontal eminence,
porion, gonion, zygion, and Whitnall's tubercle (outer canthus),
where left measurements were slightly greater than were those
of the right. Racial differences were seen in the measurements
of facial soft tissue thickness.
Introduction
In
forensic work it is not uncommon to attempt to identify the deceased
from a skull. To date in India, only the approximate age and
sex of the skull (Jit 1979) and sometimes the cause of death
(Jit 1993) can be determined by examining the skull. If data
on facial soft tissue thickness were available, it would be possible
to reconstruct the face. This type of work has been done on the
skulls of Japanese (Suzuki 1948), African Americans (Rhine and
Campbell 1980), American Caucasians (Rhine et al. 1982), and
South Africans of mixed race (Phillips and Smuts 1996). The data
generated from one population, however, cannot be applied to
another population. Lack of data on the Indian population results
in the inability to accurately reconstruct the facial features
from skeletal remains, and thus, many cases of identity and murder
go unsolved. It is, therefore, important to determine the facial
soft tissue thickness in various populations in India.
In
Japan and western countries, the following methods have been
used for measuring facial soft tissue thickness:
- Needle-depth
probe and double-edged knife (His 1895; Kollmann and Buchly 1898)
- Ultrasonography
(Lebedinskaya et al. 1993)
- Radiography
including computerized tomography (CT) scan (Aulsebrook et al.
1996; George 1987; Phillips and Smuts 1996)
Magnetic
resonance imaging (MRI) offers the following advantages over
the methods just listed:
- MRI
allows multiple planes for study, enabling researchers to take
accurate measurements of soft tissues on various anatomical points
of the cranium and face.
- A
greater number of anatomical landmarks can be studied accurately
on MRI compared to CT, where only axial sections are measured.
In
this study, an attempt was made to measure the facial soft tissue
thickness at various standard anatomical points by MRI on the
northwest Indian population.
Materials and
Methods
Facial soft tissue thickness was measured in 60 adults (30 men
and 30 women) ranging in age from 18 to 40 years who visited
the Department of Radiodiagnosis and Imaging at the Postgraduate
Institute of Medical Education and Research, Chandigarh, India,
for brain MRIs. Patients with head and neck trauma or other pathology
that could distort the normal facial structures were excluded
from the study. Subjects' age, sex, height, and weight were recorded
before taking the tissue measurements. On the basis of Indian
insurance charts that give weight against height, body mass index
(BMI) was calculated. The subjects below or equal to the 15th
percentile of BMI were considered underweight, whereas the 85th
percentile or above BMI were overweight. The subjects between
the 16th and 84th percentile were considered normal weight (Sanjeev
et al. 1991). Underweight and overweight subjects were excluded
from the study.
MRI
measured the following sections for facial soft tissue thickness
at various standard anatomical points:
- Midsagittal
section (Figures 1 and 2): from above downwards and forwards
-- vertex, supraglabella, glabella, nasion, end of nasal, midphiltrum,
upper lip margin, lower lip margin, chin-lip fold, mental eminence,
beneath chin; from above backwards and downwards-opisthocranion,
inion.
- Parasagittal
section at the level of midorbit (Figure 3): right frontal eminence,
left frontal eminence, right supraorbital, left supraorbital,
right infraorbital, left infraorbital.
- Two
coronal sections: right porion, left porion (Figure 4) right
gonion, left gonion (Figure 5).
- Three
transverse sections: right outer canthus, left outer canthus
(Figure 6), right zygion, left zygion (Figure 7), right supra
M2, and left supra M2 (Figure 8).
 |
| Figure
2
Another midsagittal section of the head indicating (1)
lower lip margin, (2) chin-lip fold, (3) mental eminence,
(4) beneath chin, (5) inion, and (6) opisthocranion. Click
here to view enlarged image. |
 |
| Figure
1
MRI in midsagittal section of the head. Outer thick white
line shows the soft tissue thickness. Landmarks indicated:
(1) vertex, (2) supraglabella, (3) glabella, (4) nasion,
(5) end of nasal, (6) midphiltrum, and (7) upper lip margin.
Click here to view enlarged
image. |
 |
| Figure
3
A parasagittal section at the level of midorbit that indicates
(1) supraorbital margin, (2) infraorbital margin, and
(3) frontal eminence. Click
here to view enlarged image. |
Observations
Table 1 illustrates that all
measurements are greater in men than in women except beneath
the chin, infraorbital, and lower lip margin. Means of the
measurements were the same in the two sexes at the end of
the nasal. Sexual differences in the mean values of all the
measurements were highly significant (p < 0.001) or significant
(p < 0.01). The end of the nasal, opisthocranion, left
gonion, and supra M2 were insignificant (p > 05). Slight
asymmetry in two sides was present at the frontal eminence,
porion, gonion, zygion, and Whitnall's tubercle (outer canthus),
where left measurements were slightly greater than right measurements.
Discussion
Determining
soft tissue thickness in cadavers may not give correct measurements
because of cadaver dehydration. To overcome this problem, Rhine
and Campbell (1980) determined the soft tissue thickness in cadavers
less than 12 hours after death or after 12 hours in refrigeration.
No data is available as to how much variation occurs during this
period. It is possible that soft tissue thickness changes on
an hourly basis. It is also possible that keeping the bodies
in refrigeration may result in rehydration. Measuring soft tissue
thickness is not easy from a plane radiograph because superimposition
of various structures causes problems in taking measurements.
A CT scan cannot take all measurements because only axial sections
are measured. Radiography and CT scans use X-ray radiation that
is harmful to biological tissues and thus is a major limiting
factor. Ultrasonography does not involve ionizing radiation and
allows real-time adjustment of planes of study. Bone may not
show well on ultrasonography, however, and the technique is operator-dependent
and does not allow adequate reliability or reproducibility. The
technique of measuring soft tissue thickness by MRI has been
used by Helmer et al. (1986) and by Lam et al. (1989). For the
purpose of this study, MRI measurements were taken.
Comparison of soft tissue thickness
in the northwest Indians with those given by Phillips and
Smuts (1996) in other populations is illustrated in Table
2.
In addition to the anatomical points evaluated in other studies,
this study evaluated additional points, vertex, opisthocranion,
inion, porion, and Whitnall's tubercle (outer canthus), which
will help in three-dimensional facial reconstruction.
Table
2 shows that the facial soft tissue thickness at various anatomical
landmarks is greater in African American men and women than those
at corresponding points in northwest Indians except at the supraorbital,
which is 4.75 mm in African American men and 5.80 mm in northwest
Indian men. Soft tissue thickness in Japanese men and women at
various anatomical points is smaller than in present material
except two measurements--the end of the nasal and the chin-lip
fold. A comparison with observations by Phillips and Smuts (1996)
on the South African mixed population indicates that most of
their measurements are more than the northwest Indians. Measurements
at the nasion, lower lip margin, supraorbital, and supra M2,
however, are higher in Indian men. Two measurements, lower lip
margin and supra M2, are higher in Indian women. Most of the
measurements in the American Caucasians are higher compared to
Indians except the midphiltrum, lower lip margin, and frontal
eminence.
References
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W. A., Becker, P. J., and Iscan, M. Y. Facial soft-tissue thickness
in the adult male Zulu, Forensic Science International
(1996) 79:83-102.
George,
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Helmer,
R. P., Koschorek, F., Terwey, B., and Frauen, T. Dickenmessung
der Gesichtsweichteile mit hilfe der Kernspin-Tomografie zum
Zwecke der Identifizierung, Archiv fur Kriminologie (1986)
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His,
W. Johann Sebastian Bach's gebeine und anlitz nebst bermerkungen
uber dessen bilder, Abhandlung durch Mathematik und Physik
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Jit,
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Kollmann,
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Lebedinskaya,
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V. M. and Smuts, N. A. Facial reconstruction: Utilization of
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Rhine,
J. S. and Campbell, H. R. Thickness of facial tissues in American
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Rhine,
J. S., Moore, C. E., and Weston, J. T. Facial Reproduction:
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Anthropology Maxwell Museum. Technical Series No. 1, University
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Sanjeev,
Indech, G. D., Jit, I., and Johnston, F. E. Skinfold thicknesses,
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Suzuki,
K. On the thickness of the soft parts of the Japanese
face, Journal of the Anthropological Society of Nippon
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